The official, who spoke on condition of anonymity, said Broadwell’s security clearance and access to classified material was suspended because of an address she gave to an alumni symposium on Oct. 26 at the University of Denver, which appeared on the video-sharing site YouTube. Broadwell holds a master's degree in international study from the school.

In the address, Broadwell talked about security at the consulate in Benghazi, Libya, where four Americans, including Ambassador Christopher Stevens, were killed in an attack.

"Any time that the Army has a reason to believe that an officer has mishandled classified information, there is grounds for such action," the Army official said, referencing the YouTube clip.

The Army has been cooperating with the FBI investigation into Broadwell. "Those actions are ongoing," the Army official said.

Broadwell, a West Point graduate and former military intelligence officer, is a lieutenant colonel in the U.S. Army Reserves, though she is not currently on active duty, according to Pentagon records obtained by NBC News.

Multiple government and law enforcement officials have told NBC News that Petraeus, a retired four-star general who is married, had an extramarital affair with Broadwell, 40. Broadwell, who also married, authored “All In,” a book about Petraeus’ leadership philosophy.

FBI investigators who looked into a series of anonymous threatening emails sent to Tampa, Fla., socialite Jill Kelley later determined they were authored by Broadwell, multiple government and law enforcement officials have told NBC News.

NBC's Jeff Black contributed to this report.

NBC's Andrea Mitchell has new details about why Jill Kelley, one of the women at the center of the scandal involving Gen. David Petraeus, initially approached an FBI agent.